I started with Bootstrap but ended up with this one - http://www.getskeleton.com http://www.getskeleton.com - as it's just 12kb uncompressed and unminified, and

I started with Bootstrap but ended up with this one - http://www.getskeleton.com http://www.getskeleton.com - as it's just 12kb uncompressed and unminified, and one file, very small but it covers enough to be productive and look nice by default.